The D5100 is not yet a sunk cost as it is within the return period so it would cost me nothing to get rid of the body. Still seems like an expensive setup:

$1000 for body + kit lens

$800 for 10-18mm

$250 for 16mm

$300 for 50mm

$1000 for Zeiss 24mm

$450 for 35mm

$350 for 55-210mm

Recheck your prices. The NEX 6 was and may still be on sale with a discount of $100-150 off the original price of $999.99. Why go crazy with so many lenses so soon. What shooting style are you most into. Portrait, distance, macro, street and so on. The 16-50 is a gem of a lens, you could stop their until you learn the camera. Some of the combinations you made are redundant. Plus the fact you left out Tamron and Sigma. Sigma has a 60mm coming out (95mm) in 35 format which looks to be nice for street shooting. Then go with a wide prime, 16 or even the 10-18 wide zoom. If you can get $400 for the Nikon then do it, more like $325. You asked is it worth it? Not if your intending to buy all that glass at once. Over time then yes. Look at my gear list, way too much and now I'm selling some items. In your case I'd go for the Sony over the Nikon. The cameras awesome and much more in the way of lenses will be produced.